/*
 * Copyright 2011 Google Inc.
 * 
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
 * in compliance with the License. You may obtain a copy of the License at
 * 
 * http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software distributed under the License
 * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
 * or implied. See the License for the specific language governing permissions and limitations under
 * the License.
 */
package com.csjung.games.gaerequest.client;

import com.google.gwt.http.client.Request;
import com.google.gwt.http.client.RequestBuilder;
import com.google.gwt.http.client.RequestCallback;
import com.google.gwt.http.client.Response;
import com.google.gwt.user.client.Window.Location;
import com.google.web.bindery.event.shared.EventBus;
import com.google.web.bindery.requestfactory.gwt.client.DefaultRequestTransport;
import com.google.web.bindery.requestfactory.shared.ServerFailure;

import com.csjung.games.gaerequest.shared.GaeHelper;

/**
 * Extends DefaultRequestTransport to handle the authentication failures reported by
 * {@link com.google.gwt.sample.gaerequest.server.GaeAuthFilter}.
 */
public class GaeAuthRequestTransport extends DefaultRequestTransport {
  private final EventBus eventBus;

  public GaeAuthRequestTransport(EventBus eventBus) {
    this.eventBus = eventBus;
  }

  @Override
  protected void configureRequestBuilder(RequestBuilder builder) {
    super.configureRequestBuilder(builder);

    /*
     * Add the redirect URL in case the user is logged out.
     * 
     * /MobileWebApp.html?parem0=value0&param1=value1#hash
     */
    String redirectUrl = Location.getPath() + Location.getQueryString() + Location.getHash();
    builder.setHeader(GaeHelper.REDIRECT_URL_HTTP_HEADER_NAME, redirectUrl);
  }

  @Override
  protected RequestCallback createRequestCallback(final TransportReceiver receiver) {
    final RequestCallback superCallback = super.createRequestCallback(receiver);

    return new RequestCallback() {
      @Override
      public void onError(Request request, Throwable exception) {
        superCallback.onError(request, exception);
      }

      @Override
      public void onResponseReceived(Request request, Response response) {
        /*
         * The GaeAuthFailure filter responds with Response.SC_UNAUTHORIZED and adds a "login" url
         * header if the user is not logged in. When we receive that combo, post an event so that
         * the app can handle things as it sees fit.
         */
        if (Response.SC_UNAUTHORIZED == response.getStatusCode()) {
          String loginUrl = response.getHeader("login");
          if (loginUrl != null) {
            receiver
                .onTransportFailure(new ServerFailure("Unauthenticated user", null, null, false));
            eventBus.fireEvent(new GaeAuthenticationFailureEvent(loginUrl));
            return;
          }
        }
        String text = response.getText();
        if (text.indexOf("Server Error: null") > 0 || text.length() == 0) {
          return;
        } else {
          superCallback.onResponseReceived(request, response);
        }

      }
    };
  }
}
